Genetic mapping of genes regulating the thymus size in back-cross rats between the laboratory BUF/Mna strain and the MITE strain derived from the wild rat, Rattus norvegicus

The thymoma prone BUF/Mna (B) rat is a useful model for Studying the genes responsible for thymus enlargement during the stage of young growth. Among the strains of rats, B rats have the largest thymuses at al stages of life. A locus, Ten-1 , which contributes to thymus enlargement in back-cross (BC) rats between the B and WKY/NCrj (W) strains, was mapped on chromosome 1. To determine the precise location of the bus, (B×(B×MITE)F1) BC rats were generated by crossing the B strain with the Inbred MITE (M) strain, which was established from captured, Japanese wild rats, and were examined by linkage study using polymerase chain reaction with 67 microsatellite markers. Linkages with thymus enlargements were found In genotypes of seven markers, BSIS, LSN, MYL2, IGF2, PBPC2, D1Mgh11 , and D1Mit6 , by X^2-test and Student's t -test, which confirmed the presence of the genetic locus associated with thymus enlargement, Ten-1 , in this region. Paradoxically, a suppressive locus, Tsu-1 , to thymus enlargement was also found on chromosome 3, showing linkages of phenotype of the small thymus with genotypes of SCN2A, CAT D3Mit16 , and D3Mit13 . By analyses of mapmaker/exp and mapmaker/qtl, Ten-1 was mapped at 4.6 cM proximal from IGF2 locus on chromosome 1 and Tsu-1 at 4.0 cM proximal from CAT locus on chromosome 3, respectively.     

A Strain Device Imposing Dynamic and Uniform Equi-Biaxial Strain to Cultured Cells

The objective of this study is to design a new apparatus to allow the control of the magnitude and frequency of dynamic stretch applied uniformly to cells cultured on a silicon elastic membrane. The apparatus is designed to produce equi-biaxial dynamic stretches with area changes ranging from 0% to 55% and frequencies ranging from 0 to 2 Hz. Homogeneous finite strain analysis using triangles of markers was performed to compute the symmetric two-dimensional Lagrangian strain tensor on the membrane. Measurements of strain in both static and dynamic conditions showed that the shear component of the strain tensor (E_rc) was near zero, and that there was no significant difference between radial (E_rr) and circumferential (E_cc) components, indicating the attainment of equi-biaxial strain. Bovine aortic endothelial cells were transiently transfected with a chimeric construct in which the luciferase reporter is driven by TPA-responsive elements (TRE). The transfected cells cultured on the membrane were stretched. The luciferase activity increased significantly only when the cells were stretched by 15% or more in area. Cells in different locations of the membrane showed similar induction of luciferase activities, confirming that strain is uniform and equi-biaxial across the membrane. © 1998 Biomedical Engineering Society. PAC98: 8780+s, 8745-k, 8722-q     

Functional associations between collagen fibre orientation and locomotor strain direction in cortical bone of the equine radius

A novel technique for determining the collagen fibre orientation pattern of cross-sections of cortical bone was used to study mid-diaphyseal sections from the equine radius. Several in vivo strain gauge studies have demonstrated that this bone is loaded in bending during locomotion in such a way that the cranial cortex is consistently subjected to longitudinal tensile strains and the caudal cortex to longitudinal compressive strains. Twenty-three radii from 17 horses were studied. All the bones obtained from adult horses exhibited a consistent pattern of collagen fibre orientation across the cortex. The cranial cortex, subjected to intermittent tension, and the lateral and medial cortices, through which the neutral axis passes, contained predominantly longitudinally oriented collagen fibres. The caudal cortex, subjected to longitudinal compression during life, contained predominantly oblique/transverse collagen. This pattern was less evident in bones from foals. Microscopic analysis of the bones studied showed that primary lamellar bone was composed of predominantly longitudinal collagen fibres, irrespective of cortex. However, there was a strong relationship between cortical location and fibre orientation within remodelled bone. Secondary osteons which formed in the caudal (compressive) cortex contained predominantly oblique/transverse collagen, while those which formed elsewhere contained longitudinal collagen. This observation explained the developmental appearance of the characteristic macroscopic pattern of collagen fibre orientation across the whole cortex in the adult. These findings provide evidence for the existence of a relationship between the mechanical function of a bone with its architecture, and now demonstrate that it extends to the molecular level.     

应变率成像在胎儿房性心律失常诊断中应用的初步探讨

目的探讨应用速度向量成像（VVI）技术对胎儿房性心律失常时心肌结构力学及形变学影响的应变与应变率研究，评价胎儿心律失常时对心肌应激状态、运动传导就及功能的影像。方法对检出的77例胎儿心律失常（其中室上性心动过速（SVT）12例、65例为频发性房性早搏（PAC））进行VVI成像技术分析，检测心律失常时胎儿心肌运动速度向量变化及对应变与应变率影响，对照组80例心率正常胎儿。结果胎儿SVT12例中7例持续发作48h者治疗前心室率250—310bpm，均合并心衰及出现水肿，VVI速度向量振幅明显降低，其应变与应变率明显低于对照组（P〈0．01）；阵发一陛SVT5例VVI速度向量振幅-过性降低，心肌应变与应变率无变化；频发PAC组示早搏时速度向量振幅改变，且运动方向同步，心肌运动三维数据定量可显示旱搏及代偿间期的三维模式，应变与应变率与对照组无差异（P〉0．05）。结论VVI成像通过心律失常心肌结构力学变化解析胎儿心律失常，特别是对胎儿心动过速时的快速心率可进行实时动态分析。及应用M型扫描法确认心动周期使胎儿心肌应变与应变率分析成为可行。     

食管分层应力-应变研究

目的　探讨食管壁各层环向应力 应变分布特征。方法　将 8只Wister大鼠的食管标记、测量在体长度后剪下置于去钙离子Krebs液中。剪下标记的中段食管用做充压试验 ,将其在显微镜下分离成内层食管 (粘膜和粘膜下层 )和外层食管 (固有肌层 )。充压时全层和分层食管均被拉长至在体长度 ,以每分钟升高 2cmH2 O速度匀速充压。根据所测图像的几何数据计算全层和分层食管的Kirchhoff应力和Green应变。零应力状态作为计算应力和应变的基本参照状态。结果　 (1 )食管离体后较在体长度缩短 2 4%。 (2 )全层食管和分层食管的环向应力 应变曲线均符合指数方程τ =(τ +β)eα(ε-ε ) -β(判定系数 >0 .96) ,为非线性关系。 (3 )与全层食管相比 ,分层后内层食管应力 应变曲线较陡直 ,且移向左侧 ,差别有统计意义 (P <0 .0 5 ) ,外层食管的曲线移向右侧 ,差别无统计意义 (P >0 .0 5 ) ,内外两层食管的应力 -应变曲线亦有统计差别 (P <0 .0 5 )。结论　食管壁各层环向应力 -应变均符合非线性关系 ,食管内层不如外层易变形     

The Complete Nucleotide Sequence of the PanAsia Strain of Foot-and-Mouth Disease Virus Isolated in Japan

The complete nucleotide sequence of the foot-and-mouth disease virus (FMDV) O/JPN/2000 strain, the PanAsia strain, was determined by cycle sequencing and primer walking. The 5 end of the genome upstream from homopolymeric poly(C) tract (S-fragment) was 367 nucleotides in length, and the remainder of the genome (L-fragment), excepting the poly(A) tail, was 7808 nucleotides. The L-fragment contains a single open reading frame of 6996 nucleotides terminating at a UAA codon 96 bases from the 3 poly(A) sequence. Comparison of sequences shows that the length of the structural and non-structural protein coding regions are identical to those in the O1/Kaufbeuren strain, and no striking differences such as deletion or insertion were observed between them.     

Psychological functioning across stages of treatment for infertility

Psychological functioning was examined for a cross section of 104 couples in different stages of medical investigation for infertility. Couples were separated into three stages based upon the length of time they had been pursuing medical treatment for infertility: year 1, year 2, and year 3 and beyond. Emotional strain was moderately elevated during the first year, returned to more normal levels during the second year, and showed marked increases beyond year 3. Indices of marital adjustment and sexual satisfaction were stable across the first two stages but deteriorated after the third year. These data suggest that the stage of treatment may exert a major influence upon psychological functioning for infertile couples pursuing medical assistance. The results are consistent with a model of psychological strain that reflects an acute stress reaction to the initial diagnosis and treatment overlaid with a chronic strain response to longer-term treatment.Research was aided by a grant-in-aid of research from Sigma Xi, The Scientific Research Society, a research fellowship from the University of South Carolina, and NIMH Institutional Training Grant MH-15930.     

Biomechanical Properties of Esophagus during Systemic Treatment with Epidermal Growth Factor in Rats

The epidermal growth factor (EGF) is a growth factor with effects on many cell types and tissue. Morphometric and passive biomechanical properties were studied in isolated segments of the esophagus in 22 EGF-treated rats and 12 control rats. The rats were divided into groups with EGF treatment for 2, 4, 7, and 14 days (n=6 for each group except n=4 for the 14 days EGF-treatment group) or saline treatment (n=3 for each group). The mechanical test was performed as a distension experiment in vitro where the whole esophagus was stretched to its in situ length and distended with pressures up to 10 cm H₂O using a ramp distension protocol. The pressure and outer diameter were recorded. Circumferential stress (force per area) and strain (deformation) were computed from the diameter and pressure data using the zero-stress state as reference. The zero-stress state was obtained by cutting esophageal rings radially. This caused the rings to open up into a sector. EGF induced pronounced morphometric changes, e.g., the wall thickness, wall cross-sectional area, and inner and outer circumferential lengths significantly increased during the EGF treatment. Histological analysis showed mucosa and submucosa growth during EGF treatment. The opening angle and residual strains increased with the highest value in the 14 days EGF-treated group (P < 0.05). The change in opening angle depended largely on the change in mucosa thickness. Furthermore, the circumferential stiffness of the esophagus reached a maximum after 7 days EGF treatment (P < 0.01). © 2003 Biomedical Engineering Society. PAC2003: 8719Rr, 8717Ee     

Fine mapping of thymus enlargement gene 1 (Ten1) in BUF/Mna rats

Two polymeric autosomal loci, Ten1 and Ten2, regulate thymus enlargement in BUF/Mna (B) rats. Previously, we mapped Ten1 on chromosome (Chr) 1 to a 20 cM region between Myl2 and D1Mgh11, and Ten2 on Chr 13. To further characterize the precise position of Ten1, 34 and 37 microsatellite markers, that have a polymorphism between the B and WYK (W) and between the B and MITE (M) strains, were used for linkage analysis of thymus enlargement in 105 (WBF1 x B) blackcross (BC) and 78 (B x BMF1) BC rats, respectively. Our data showed that the D1Rat168, D1Rat112, D1Rat323, D1Got186, D1Got187 and D1Got188 markers each gave a peak logarithm of odds (LOD) score of 10.68 for linkage to the thymus ratio in (WBF1 x B) BC rats, and that the D1Rat168, D1Rat197, D1Got184, D1Got186 and D1Got188 markers each gave a peak LOD score of 7.82 in (B x BMF1) BC rats. The two LOD score peaks are coincident in the position of the rat genetic map. All of the markers mentioned above are located in the region between Igf2 and D1Mgh11, in which synteny is conserved with human 11q15.5 and the distal end of mouse Chr 7 or with human 11q13 and the proximal end of mouse Chr 19. Genes existing in these regions are discussed as candidate genes for Ten1.     

Predictability of Individual Differences in Activation Processes in a Field Setting Based on Laboratory Measures

The predictability of individual differences in activation processes was investigated in a multi-method laboratory-field study. Male students of physical education (N=58) were examined under various emotionally activating and physically demanding conditions (mental arithmetic, reaction time, free speech, cold pressor test, bicycle ergometer). The assessment included multi-channel recordings of pre-start phases in an athletic stadium and performance on a 1000 m run. Basal heart rate was also recorded during sleep. This multi-situational assessment was repeated after three weeks, three months, and, for most (N=42) subjects, after one year. Significant relationships exist between scores from corresponding conditions of relaxation, anticipation, and performance of physical exercise. However, with the exception of heart rate, correlation coefficients are rather small and seem to be of questionable predictive validity. A generalizability study further supports the general conclusion: To increase the practical relevance in psychophysiological investigations of stress/strain phenomena, such studies should directly assess individual differences in the criterion situations themselves.